Core Java Interview Questions 1 What is the difference between an Abstract class and Interface?

9) Why there are some null interface in java ? What does it
mean ? Give me some null interfaces in JAVA?
Null interfaces act as markers..they just tell the compiler that the objects of this class need
to be treated differently..some marker interfaces are : Serializable, Remote, Cloneable
10) Is synchronised a modifier?indentifier??what is it??
It's a modifier. Synchronized methods are methods that are used to control access to an
object. A thread only executes a synchronized method after it has acquired the lock for the
method's object or class. Synchronized statements are similar to synchronized methods. A
synchronized statement can only be executed after a thread has acquired the lock for the
object or class referenced in the synchronized statement.